ParaView vtkStructuredGrid

int dg_reader::RequestData(vtkInformation * request, vtkInformationVector ** inVec, vtkInformationVector *outVec)
{
  vtkInformation *info = outVec->GetInformationObject(0);
  // get the output
  vtkStructuredGrid *grid = vtkStructuredGrid::SafeDownCast(info->Get(vtkStructuredGrid::DATA_OBJECT()));

  // create data
  vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
  size_t numi = 2;
  size_t numj = 3;
  size_t numk = 1;
  grid->SetExtent(0, numj, 0, numj, 0, numj);
  for(size_t k = 0; k < numk; ++k)
  {
    for(size_t j = 0; j < numj; ++j)
    {
      for(size_t i = 0; i < numi; ++i)
      {
        points->InsertNextPoint(i, j, k);
      }
    }
  }

  grid->SetDimensions(numi, numj, numk);
  grid->SetPoints(points);

  vtkSmartPointer<vtkDoubleArray> density = vtkSmartPointer<vtkDoubleArray>::New();
  density->SetName("density");
  density->SetNumberOfComponents(1);
  density->SetNumberOfValues(points->GetNumberOfPoints());
  for(size_t i = 0; i < points->GetNumberOfPoints(); ++i)
  {
    density->SetComponent(i, 0, i);
  }
  grid->GetPointData()->AddArray(density);
  std::cout << grid->GetNumberOfPoints() << " points" << std::endl;
  std::cout << grid->GetNumberOfCells() << " cells" << std::endl;
  return 1;
}